1. Technical Field
The present invention relates to a combustion apparatus provided with a combustion box which has, on an upper end thereof, a connection flange part for connecting thereto a heat exchanger.
2. Background Art
As this kind of combustion apparatus, there is known one comprising: a partition plate inside a combustion box in order to partition space inside the combustion box into a combustion chamber and an air supply chamber which lies under the combustion chamber; and a plurality of burners which are laterally arrayed, each of the burners being longitudinally elongated with flame holes on an upper end thereof such that air can be supplied from the air supply chamber to the combustion chamber through a multiplicity of distribution holes formed in the partition plate (see, e.g., JP-A-2011-252671).
By the way, in this kind of combustion apparatus provided with the combustion box, there are cases in which Helmholtz type resonant frequency may give rise to larger resonance sounds in consonance with a frequency of the combustion vibrations. Here, the Helmholtz type resonance frequency lowers by increasing an internal volume of the combustion box. Therefore, by increasing the internal volume of the combustion box to thereby make the Helmholtz type resonance frequency lower than the frequency of the combustion vibrations, the occurrence of the resonance sounds can be restrained.
However, if the height dimension of the combustion box is increased in order to increase the internal volume of the combustion box, the distance between the heat exchanger and the burners will become larger, resulting in a poorer thermal efficiency. In addition, if the lateral dimension or the longitudinal dimension of the entire combustion box is increased, the connection flange part on the upper end of the combustion box will also become larger. It therefore becomes necessary to modify the heat exchanger that is connected to the connection flange part. For that reason, it has currently been not practiced to increase the internal volume of the combustion box in order to restrain the occurrence of the resonance sound